Depositing material with antimicrobial properties on permeable substrate using atomic layer deposition

ABSTRACT

Embodiments relate to depositing a layer of antimicrobial material such as silver on a permeable substrate using atomic layer deposition (ALD). A deposition device includes two injectors that inject source precursor, reactant precursor, purge gas or a combination thereof onto the permeable substrate that passes between the injectors. Part of the gas injected by an injector penetrates the permeable substrate and is discharged by the other injector. The remaining gas injected by the injector moves in parallel to the surface of the permeable substrate and is discharged via an exhaust portion formed on the same injector. While penetrating the substrate or moving in parallel to the surface, the source precursor or the reactant precursor becomes absorbed on the substrate or react with precursor already present on the substrate to deposit the antimicrobial material on the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(e) to co-pendingU.S. Provisional Patent Application No. 61/511,025, filed on Jul. 23,2011, which is incorporated by reference herein in its entirety.

BACKGROUND

1. Field of Art

The disclosure relates to depositing silver or a silver compound on apermeable substrate such as a membrane or fabric to afford antimicrobialproperties to the substrate.

2. Description of the Related Art

Permeable substrates such as membrane and fabric have variousapplications. The permeable substrates may be deposited with certainmaterials to enhance or modify various properties. Such propertiesinclude antimicrobial properties. The permeable substrates withantimicrobial properties may be used for applications that involvesanitizing materials or body parts coming into contact with thepermeable substrates from microbes. Example applications of permeablesubstrates with antimicrobial properties include medical equipment andhouse cleaning products.

Silver and silver compounds are well known to have superb antimicrobialproperties. To take advantage of antimicrobial properties of silver orsilver compounds, permeable substrates can be coated or deposited withsilver for silver compounds or various medical or health-relatedapplications. However, silver is a precious metal and is costly.Therefore, fabric or textile coated with silver or silver compoundstends to be expensive. Moreover, the quality of silver or silvercompound coated on such fabric or textile tend to be inconsistent andnon-conformal, reducing the overall efficacy of the silver or silvercompound coated on such permeable substrates.

SUMMARY

Embodiments relate to depositing silver or a silver compound on apermeable substrate by atomic layer deposition (ALD). Source precursorfor performing ALD is injected on a portion of the permeable substrate.Reactant precursor for performing ALD is injected on the portion of thepermeable substrate by a reactant injector. The reactant precursor inconjunction with the source precursor on the permeable substrate formssilver or the silver compound on the permeable substrate. Relativemovement of the permeable substrate with respect to both the sourceinjector and the reactant injector is caused to inject the sourceprecursor and the reactant precursor on another portion of the permeablesubstrate.

Embodiments also relate to an antimicrobial article of manufacture thatincludes a permeable substrate and silver or a silver compound depositedon the permeable substrate. The silver or the silver compound isdeposited on the permeable substrate by performing ALD. ALD includesinjecting source precursor on a portion of the permeable substrate andinjecting reactant precursor on the portion of the permeable substrate.The reactant precursor reacts or replaces the source precursor to formsilver or the silver compound on the permeable substrate.

Embodiments also relate to a deposition device for depositing silver ora silver compound on a permeable substrate by ALD. The deposition deviceincludes a source injector, a reactant injector, and a moving mechanism.The source injector injects source precursor on a portion of thepermeable substrate. The reactant injector generates and injectsradicals onto the portion of the permeable substrate injected with thesource precursor. The reactant injector is formed with a chamber forreceiving gas and includes electrodes for generating plasma in thechamber by application of voltage difference across the electrodes. Theradicals in conjunction with the source precursor on the permeablesubstrate form silver or the silver compound on the permeable substrateby ALD. The movement mechanism causes relative movement of the permeablesubstrate relative to the source injector and the reactant injector toform silver or the silver compound on other portions of the permeablesubstrate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a deposition device, according to oneembodiment.

FIG. 2 is a cross sectional view of the deposition device of FIG. 1taken along line A-B, according to one embodiment.

FIGS. 3A through 3C are cross sectional views of a permeable substrateat different stages of a process associated with coating silver orsilver compound, according to one embodiment.

FIG. 4 is a flowchart illustrating processes of manufacturing apermeable substrate deposited with silver or a silver compound,according to one embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments are described herein with reference to the accompanyingdrawings. Principles disclosed herein may, however, be embodied in manydifferent forms and should not be construed as being limited to theembodiments set forth herein. In the description, details of well-knownfeatures and techniques may be omitted to avoid unnecessarily obscuringthe features of the embodiments.

In the drawings, like reference numerals in the drawings denote likeelements. The shape, size and regions, and the like, of the drawing maybe exaggerated for clarity.

Embodiments relate to depositing a layer of antimicrobial material suchas silver or a silver compound on a permeable substrate using atomiclayer deposition (ALD). A deposition device includes one or moreinjectors that inject source precursor, reactant precursor, purge gas ora combination thereof onto the permeable substrate as the permeablesubstrate passes between the injectors. Part of the gas injected by aninjector penetrates the permeable substrate and is discharged by theother injector. The remaining gas injected by the injector moves inparallel to the surface of the permeable substrate and is discharged viaan exhaust portion formed on the same injector. While penetrating thesubstrate or moving in parallel to the surface, the source precursor orthe reactant precursor becomes absorbed on the substrate or react withprecursor already present on the substrate to deposit the antimicrobialmaterial on the substrate.

Permeable substrate described herein refers to a substrate having aplanar structure where at least part of gases or liquids injected on oneside of the substrate can penetrate to the opposite side of thesubstrate. The permeable substrate includes, among others, textile,membrane and fabric, and web. The permeable structure may be made ofvarious materials including, among other materials, paper, polyethylene,porous metal, wool, cotton and flax.

Example Deposition Device

FIG. 1 is a perspective view of a deposition device 100, according toone embodiment. The deposition device 100 may include, among othercomponents, an upper reactor 130A and a lower reactor 130B. A permeablesubstrate 120 moves from the left to right (as indicated by arrow 114)and passes between the upper and lower reactors 130A, 130B, depositingthe permeable substrate 120 with a layer 140 of material. The entiredeposition device 100 may be enclosed in a vacuum or in a pressurizedvessel.

Although the deposition device 100 is illustrated as depositing materialon the substrate 120 as the substrate moves horizontally, the depositiondevice 100 may be oriented so that the layer 140 is deposited as thesubstrate 120 moves vertically or in a different direction.

The upper reactor 130A is connected to pipes 142A, 146A, 148A supplyingprecursor, purge gas and a combination thereof into the upper reactor130A. Exhaust pipes 152A and 154A are also connected to the upperreactor 130A to discharge excess precursor and purge gas from theinterior of the upper reactor 130A. The upper reactor 130A has its lowersurface facing the substrate 120.

The lower reactor 130B is also connected to pipes 142B, 146B, 148B toreceive precursor, purge gas and a combination thereof. Exhaust pipes(e.g., pipe 154B) are also connected to the lower reactor 130B todischarge excess precursor and purge gas from the interior of the lowerreactor 130B. The lower reactor 130B has its upper surface facing thesubstrate 120.

The deposition device 100 may perform atomic layer deposition (ALD) onthe substrate 120 as the substrate 120 moves from the left to the rightbetween the lower surface of the upper reactor 130A and the uppersurface of the lower reactor 130B. ALD is performed by injecting sourceprecursor on the substrate 120 followed by injection of the reactantprecursor on the substrate 120.

FIG. 2 is a cross sectional view of the deposition device 100 takenalong line A-B of FIG. 1, according to one embodiment. The upper reactor130A may include, among other components, a source injector 202 and areactant injector 204. The source injector 202 is connected to the pipe142A to receive the source precursor (in combination with carrier gassuch as Argon) and the reactant injector 204 is connected to the pipe148A to receive gas for generating desired reactant precursor (incombination with carrier gas such as Argon). The carrier gas may beinjected via a separate pipe (e.g., pipe 146A) or via the pipes thatsupply the source or gas for generating the reactant precursor. Themultiple reactors can be arranged in a different sequence. For example,a reactant injector 204 may be placed to the left of a source injector202 assuming that the substrate 280 moves from the left to the right.

The body 210 of the source injector 202 is formed with a channel 242,perforations (e.g., holes or slits) 244, a reaction chamber 234, aconstriction zone 260 and an exhaust portion 262. The source precursorflows into the reaction chamber 234 via the channel 242 and theperforations 244, and reacts with the permeable substrate 120. Part ofthe source precursor penetrates the substrate 120 and is discharged viaan exhaust portion 268 formed on the lower reactor 130B. The remainingsource precursor flows through the constriction zone 260 in parallel tothe surface of the substrate 120 and is discharged via the exhaustportion 262. The exhaust portion is connected to the pipe 152A anddischarges the excess source precursor out of the injector 202.

When the source precursor flows through the constriction zone 260,excess source precursor is removed from the surface of the substrate 120due to the higher speed of the source precursor in the construction zone260. In one embodiment, the height M of the constriction zone 260 isless than ⅔ the height Z or the width W of the reaction chamber 234.Such height M is desirable to remove the source precursor from thesurface of the substrate 120.

The reactant injector 204 may include, among other components, a body214 and an electrode 247 extending across the body 214. Gas supplied bythe pipe 146A is injected into a plasma chamber 246 via a channel 245.By applying a voltage signal between the inner electrode 247 and anouter electrode (i.e., the body 214), plasma is generated in the plasmachamber 246. As a result, radicals are generated in the plasma chamber246 and flow into reaction chamber 236. The radicals function asreactant precursor that interact or replace source precursor moleculeson the substrate 120.

Part of the excess radicals (generated by the reactant injector 204)pass through a constriction zone 264 and are discharged via an exhaustportion 266. The exhaust portion 266 is connected to the pipe 154B. Theremaining excess radicals penetrate the substrate 120, and aredischarged via an exhaust portion formed in the injector 208.

The lower reactor 130B has a structure similar to the upper reactor 130Abut has an upper surface facing in a direction opposite to the upperreactor 130A. The lower reactor 130B may include a source injector 206and a reactor injector 208. The source injector 206 receives the sourceprecursor via the pipe 142B and injects the source precursor onto therear surface of the substrate 120. Part of the source precursorpenetrates the substrate 120 and is discharged via the exhaust portion262. The remaining source precursor flows into the exhaust portion 268in parallel to the surface of the substrate 120 and is discharged fromthe source injector 206.

The structure of the reactor injector 208 is substantially the same asthe reactor injector 204, and therefore, detailed description thereof isomitted herein for the sake of brevity.

The deposition device 100 may also include a mechanism 280 for movingthe substrate 120. The mechanism 280 may include a motor or an actuatorthat pulls or pushes the substrate 120 to the right direction asillustrated in FIG. 2. As the substrate 120 is moved progressively tothe right, substantially entire surface of the substrate 120 is exposedto the source precursor and the reactant precursor, depositing materialon the substrate 120 as a result.

By having an opposing set of reactors, the source precursor and thereactant precursor flow perpendicular to the surface of the substrate120 as well as in parallel to the surface of the substrate 120.Therefore, a layer of conformal material is deposited on the flatsurface as well as the pores or holes in the substrate 120. Hence, thematerial is deposited more evenly and completely on the substrate 120.

In order to reduce the precursor material leaked outside the depositiondevice 100, the distance H between the substrate 120 and the upper/lowerreactor 130A, 130B is maintained at a low value. In one embodiment, thedistance H is less than 1 mm, and more preferably less than hundreds ofμms.

In one embodiment, Ag(fod)(PEt₃)(fod=2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) or(2,2-dimethylpropionato)silver(I)triethylphosphine: Ag(DMP)(TEP) is usedas the source precursor. H* radicals may be used as reactant precursor.H* radicals may be generated by injecting H₂ into the plasma chambers ofthe reactant injectors 204, 208 and applying voltage signal across theirinner and outer electrodes. In one embodiment, direct current (DC)pulses of approximately 300 kHz are applied to the inner electrodes andthe outer electrodes to generate plasma in the chambers.

Instead of or in addition to depositing silver, silver compounds such asAg_(X)Al_(1-X), Ag_(X)Al_(1-X)O, Ag_(X)Si_(1-X), Ag_(X)Si_(1-X)O,Ag_(X)Ni_(1-X), Ag_(X)Ni_(1-X)O, Ag_(X)Ti_(1-X), or Ag_(X)Ti_(1-X)O maybe deposited on the permeable substrate 120. To deposit Ag_(X)Al_(1-X)or Ag_(X)Al_(1-X)O, TMA (trimethylaluminum) may be used as the sourceprecursor. To deposit Ag_(X)Ti_(1-X), or Ag_(X)Ti_(1-X)O, TEMATi(tetraethylmethylaminotitanium) may be used as the source precursor. Todeposit Ag_(X)Si_(1-X), or Ag_(X)Si_(1-X)O, HMDSN(hexa-methyl-disilazane) may be used as the source precursor. To depositAg_(X)Cu_(1-X) or Ag_(X)Cu_(1-X)O, di-iso-propylacetamidinato-copper orCu beta-diketonates may be used as the source precursor. To depositAg_(X)Ni_(1-X) or Ag_(X)Ni_(1-X)O, nickel-dialkylamino-alkoxidecomplexes [Ni(dmamp)₂, Ni(emamp)₂, and Ni(deamp)₂] orbis(cyclopentadienyl)nickel (NiCp₂) as may be used as the sourceprecursor. These silver compounds are non-stoichiometric compounds andhave antimicrobial properties.

Instead of using H* radicals, hydrogen-containing precursors such asNH₃, CH₄, B₂H₆ or reducing agents such as CO may be used as reactantprecursor.

In one embodiment, one or more purge gas injectors may be placed betweenthe reactors 202, 204 and/or the reactors 206, 208 to inject purge gasonto the substrate 120. The gas injector may have the same structure asthe injectors 202, 206 except that the purge gas is injected into thegas injectors instead of source precursor. By injecting the purge gas,any excess source precursor molecules (e.g., physisorbed sourceprecursor molecules) on the substrate 120 may be removed before exposingthe substrate 120 to the reactant precursor. In this way, the layer ofsilver or silver compounds (e.g., silver oxide or non-stoichiometricsilver compounds) may be deposited on the substrate 120 becomes moreeven and consistent.

The deposition device 100 of FIGS. 1 and 2 are merely illustrative.Different type of depositing devices may inject source precursormaterial and reactant precursor material onto a substrate to depositsilver on the substrate. For example, a deposition device may includereactors at one side of the substrate (e.g., reactors 202, 204) but notat the other side of the substrate.

Permeable Substrate Deposited with Silver or Silver Compound

FIG. 3A is a cross sectional view of the permeable substrate 120deposited with an intermediate layer 310 and a layer 320 of silver orsilver compounds, according to one embodiment. If the permeablesubstrate 120 includes textile or polymer fibers, silver or silvercompounds deposited on the permeable substrate 120 may lack adhesioncompared to aluminum, silicon, titanium or oxides containing theseatoms. In order to improve the adhesion of silver or silver compoundsand provide uniform deposition thickness, a stable intermediate layer310 may be deposited on the permeable substrate 120 before depositingsilver or silver compounds on the substrate 120. Silver compounds suchas silver oxide or non-stoichiometric silver compounds can be depositedon the permeable substrate 120 without an intermediate layer 310.

In one embodiment, the intermediate layer includes SiO₂, Al₂O₃ or TiO₂.The layer 320 of silver or silver compounds can be deposited on theintermediate layer using, for example, the deposition device 100described above in detail with reference to FIGS. 1 and 2.

FIG. 3B is a cross section view of the permeable substrate 120 where thesilver particles or silver compound particles are coalesced intonano-sized bumps 324 having width or length ranging from few nanometersto 50 nm, according to one embodiment. By forming bumps 324, the surfacearea of the silver or the silver compounds can be increased for enhancedantimicrobial efficiency. The bumps 324 may be formed, for example, byheat-treating the silver layer 320 under inert environment or H₂environment, or performing hydrogen radical annealing to decreaseannealing temperature with H₂ remote-plasma. Such treatment causes thesilver particles or silver compound particles to self-agglomerate andcreate bumps 324. The bumps 324 may have regular shapes (e.g.,semispherical shape) or irregular shapes.

FIG. 3C is a cross sectional diagram of the substrate 120 deposited witha diffusion barrier 330 on the bumps 324, according to one embodiment.The bumps 324 may be deposited with the diffusion barrier 330 to preventactive substances in the environment from reacting with silver or asilver compound and degrading the antimicrobial properties of the silveror the silver compound. In one embodiment, material such as SiO₂, Al₂O₃and TiO₂ may be used as material for the diffusion barrier. Thethickness of the diffusion barrier 330 may be in the range of 5 to 10nm.

Process for Manufacturing Permeable Substrate Deposited with Silver orSilver Compound

FIG. 4 is a flowchart illustrating the processes of manufacturing apermeable substrate deposited with silver or silver compound, accordingto one embodiment. The intermediate layer 310 is deposited 406 on thepermeable substrate 120 by using ALD or other deposition methods. Then,a layer 320 of silver is deposited 410 on the intermediate layer 310using ALD. For this purpose, the deposition device 100 of FIGS. 1 and 2may be used.

The self-agglomeration of silver or the silver compound is induced 414by subjecting the permeable substrate 120 to processes such asheat-treatment or radical annealing. As a result, bumps 324 are formedon the intermediate layer 310. The diffusion barrier layer 330 is thendeposited with a diffusion barrier 330 to protect the agglomeratedsilver or the silver compound against external influences.

The method described above with reference to FIG. 4 is merelyillustrative. One or more steps (e.g., step 406 of forming anintermediate layer, step 414 of inducing self-agglomeration, and step418 of depositing diffusion barrier) may be omitted.

Although above embodiments were described primarily with reference todepositing silver or silver compound on a permeable substrate, othermaterials (e.g., nickel) with antimicrobial properties may be depositedon the permeable substrate using ALD.

Depositing silver or other materials with antimicrobial properties onpermeable substrate using ALD is advantageous, among other reasons,because silver, silver compounds, or other materials can be depositedthinly on the permeable substrate in a conformal manner. The thindeposition enables the permeable substrate to retain permeability andother functions of the permeable substrate while affording antimicrobialproperties to the permeable substrate.

Although the present invention has been described above with respect toseveral embodiments, various modifications can be made within the scopeof the present invention. Accordingly, the disclosure of the presentinvention is intended to be illustrative, but not limiting, of the scopeof the invention, which is set forth in the following claims.

1. A method of depositing silver or a silver compound on a permeablesubstrate, comprising: injecting source precursor for performing atomiclayer deposition (ALD) on a portion of the permeable substrate by asource injector; injecting reactant precursor for performing ALD on theportion of the permeable substrate by a reactant injector, the reactantprecursor in conjunction with the source precursor on the permeablesubstrate forming the silver or the silver compound on the permeablesubstrate; and causing relative movement of the permeable substraterelative to the source injector and the reactant injector to inject thesource precursor and the reactant precursor on another portion of thepermeable substrate.
 2. The method of claim 1, wherein the sourceprecursor comprises at least one of Ag(fod)(PEt₃)(fod=2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) or(2,2-dimethylpropionato)silver(I)triethylphosphine: Ag(DMP)(TEP).
 3. Themethod of claim 1, wherein the silver compound comprises at least one ofAg_(X)Al_(1-X), Ag_(X)Al_(1-X)O, Ag_(X)Si_(1-X), Ag_(X)Si_(1-X)O,Ag_(X)Ni_(1-X), Ag_(X)Ni_(1-X)O, Ag_(X)Ti_(1-X), or Ag_(X)Ti_(1-X)O. 4.The method of claim 2, wherein the reactant precursor is H* radicals. 5.The method of claim 1, further comprising depositing an intermediatelayer on the permeable substrate before forming the silver or the silvercompound on the permeable substrate.
 6. The method of claim 5, whereinthe intermediate layer comprises at least one of SiO₂, Al₂O₃ or TiO₂. 7.The method of claim 1, further comprising depositing a diffusion barrieron the formed silver or the silver compound.
 8. The method of claim 6,wherein the diffusion barrier comprises at least one of SiO₂, Al₂O₃ orTiO₂.
 9. The method of claim 1, further comprising forming nano-sizedbumps by inducing self-agglomeration of the formed silver or the silvercompound.
 10. An antimicrobial article of manufacture, comprising: apermeable substrate; and silver or a silver compound deposited on thepermeable substrate by performing atomic layer deposition, the atomiclayer deposition performed by injecting source precursor on a portion ofthe permeable substrate and injecting reactant precursor forming thesilver or the silver compound in conjunction with the source precursoron the portion of the permeable substrate.
 11. The antimicrobial articleof claim 10, wherein the source precursor comprises at least one ofAg(fod)(PEt₃)(fod=2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) or(2,2-dimethylpropionato)silver(I)triethylphosphine: Ag(DMP)(TEP). 12.The antimicrobial article of claim 10, wherein the silver compoundcomprises at least one of Ag_(X)Al_(1-X), Ag_(X)Al_(1-X)O,Ag_(X)Si_(1-X), Ag_(X)Si_(1-X)O, Ag_(X)Ni_(1-X), Ag_(X)Ni_(1-X)O,Ag_(X)Ti_(1-X), or Ag_(X)Tl_(1-X)O.
 13. The antimicrobial article ofclaim 10, wherein the reactant precursor is H* radicals.
 14. Theantimicrobial article of claim 10, further comprising an intermediatelayer deposited between the permeable substrate and the silver or thesilver compound.
 15. The antimicrobial article of claim 14, wherein theintermediate layer comprises at least one of SiO₂, Al₂O₃ or TiO₂. 16.The antimicrobial article of claim 10, further comprising a diffusionbarrier deposited on the silver or the silver compound.
 17. Theantimicrobial article of claim 16, wherein the diffusion barriercomprises at least one of SiO₂, Al₂O₃ or TiO₂.
 18. The antimicrobialarticle of claim 10, further comprising nano-sized bumps formed byinducing self-agglomeration of the formed silver or the silver compound.19. A deposition device for depositing silver or a silver compound on apermeable substrate, comprising: a source injector configured to injectsource precursor on a portion of the permeable substrate; a reactantinjector configured to generate and inject radicals onto the portion ofthe permeable substrate injected with the source precursor, the reactantinjector formed with a chamber for receiving gas and comprisingelectrodes for generating plasma in the chamber by application ofvoltage difference across the electrodes, the radicals in conjunctionwith the source precursor on the permeable substrate forming silver or asilver compound on the permeable substrate by atomic layer deposition(ALD); and a mechanism for causing relative movement of the permeablesubstrate relative to the source injector and the reactant injector toform silver or the silver compound on other portions of the permeablesubstrate.
 20. The deposition device of claim 19, further comprisinganother injector at an opposite side of the permeable substrate toinject the source precursor or the radicals on the permeable substrate,at least part of the source precursor or the radicals injected by thesource injector or the reactant injector discharged via the otherinjector.